Electronic apparatus

ABSTRACT

There is provided an electronic apparatus having a novel means capable of suppressing temperature rise of a heat generating element. The electronic apparatus ( 20 ), which includes a heat generating element, is provided with a device (or a chemical heat pump) ( 10 ) comprising: a reaction chamber ( 1 ) containing a chemical heat storage material showing an endothermic reaction in response to heat emitted by the heat generating element ( 11 ); a condensation/evaporation chamber ( 3 ) for condensing or evaporating a condensable component produced from the endothermic reaction of the chemical heat storage material; and a communication part ( 5 ) communicating the reaction chamber ( 1 ) with the condensation/evaporation chamber ( 3 ) such that the condensable component is movable between the reaction chamber ( 1 ) and the condensation/evaporation chamber ( 3 ).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electronic apparatus, more particularly to an electronic apparatus including a heat generating element (or an element or component which generates heat).

2. Description of the Related Art

With respect to electronic elements installed in an electronic apparatus, for example, integrated circuit (IC) such as a central processing unit (CPU), etc., a part of the input energy is lost by being converted into heat and generating(emitting) the heat. If the heat generation brings about significant temperature rise, the electronic element itself may fail and/or other peripheral components may be adversely affected, so that the lifetime and reliability of the electronic apparatus may be impaired. In addition, the heat generation of the electronic element is undesirable also from the viewpoints of safety and usability by a user of the electronic apparatus.

In order to suppress the temperature rise of such a heat generating element, there are conventionally known methods that a cooling fan is used to exhaust the heat outside of the electronic apparatus by forced convection, and that a heat pipe is connected at its ends respectively to the heat generating element and to a heat sink or a heat dissipation plate to transport the heat by using latent heat for evaporation and condensation of a working fluid in the heat pipe and then to dissipate the heat from the heat sink or the like (see, for example, Patent Literature 1). These methods suppress the temperature rise of the heat generating element by dissipating the heat directly or indirectly from the heat generating element.

Patent Literature 1: JP 2001-68883 A

Patent Literature 2: JP 10-89799 A

Patent Literature 3: JP 2008-111592 A

BRIEF SUMMARY OF THE INVENTION

In recent years, as the performance of electronic apparatuses is getting higher, the number of heat generating elements installed in one electronic apparatus is increased and the amount of energy input to the respective heat generating elements is increased, so that the amount of heat generated in the electronic apparatus is increased.

The conventional method using a cooling fan requires additional energy to drive the cooling fan. Since this method brings about larger power consumption of the electronic apparatus to obtain higher heat dissipation capability, it is not preferable. Fundamentally, with respect to the heat generation which loses energy, this method intends to radiate the heat by inputting energy, and therefore it is not efficient. In addition, it requires a relatively large space to install the cooling fan, so that this method is not suitable for small electronic apparatuses. Furthermore, in a case of electronic apparatuses of which the housing is sealed, e.g. smartphones and tablet devices, it is not possible that an air flow caused by the cooling fan is emitted outside of the apparatus.

Further, the conventional method using a heat pipe may transport heat promptly, but it requires a heat sink or a heat dissipation plate to dissipate the heat. It requires a relatively large space to install the heat sink or the like, so that this method is not suitable for small electronic apparatuses. Instead of the heat sink or the like, it may be considered to dissipate heat to the housing or so of the electronic apparatus. However, since the size and thickness of electronic apparatuses tend to be smaller, the surface area of the housing becomes small, so that it is not possible to obtain a high heat dissipation capability. In addition, the temperature of the housing is elevated too much, which is not preferable in terms of safety and usability by a user. Furthermore, in a case of high-performance mobile apparatuses, e.g. smartphones, which has a problem of a shorter lifetime of a lithium ion battery, when heat is transferred to the housing, the ambient temperature of the lithium ion battery increases, which may lead to aging deterioration of a battery capacity.

Under the condition as described in the above, the fact is that a temperature of each of the heat generating elements is measured, and the amount of energy input to the heat generating element is limited when the measured value of the temperature exceeds a predetermined threshold value. This method is to suppress the temperature rise of the heat generating element by reducing the very amount of heat generated by the heat generating element. However, this method results in interruption of functions of the heat generating element (e.g. performance of a CPU) in every time of the temperature rise of the heat generating element, so that this method is conducted at the expense of the performance of the electronic apparatus.

The present invention aims to provide an electronic apparatus having a novel means capable of suppressing temperature rise of a heat generating element.

The present inventors have focused on techniques for storing and transferring heat by using a chemical reaction, i.e. a chemical heat pump. Currently, chemical heat pumps are used for the purpose of waste heat utilization in chemical plants or power plants, and used in large apparatuses such as a hot-water supply and heating system in households or a refrigeration car (see, for example, Patent Literatures 2 and 3). However, a chemical heat pump applied to an electronic apparatus is not known. The present inventors have been dedicated to consider based on our unique concept of using a chemical heat pump as novel means capable of suppressing the temperature rise of a heat generating element, and thereby have accomplished the present invention.

According to the first aspect of the present invention, there is provided an electronic apparatus comprising:

a heat generating element; and

a device comprising: a reaction chamber containing a chemical heat storage material which shows an endothermic reaction in response to heat emitted by the heat generating element; a condensation/evaporation chamber for condensing or evaporating a condensable component produced from the endothermic reaction of the chemical heat storage material; and a communication part which communicates between the reaction chamber and the condensation/evaporation chamber such that the condensable component is able to move between the reaction chamber and the condensation/evaporation chamber through the communication part.

The present invention is not limited in any way, but the device in which a reaction chamber and a condensation/evaporation chamber communicate with each other by a communication part may be understood as a so-called chemical heat pump. In this specification, such a device is also referred to as a chemical heat pump.

In one embodiment related to the first aspect of the present invention, the reaction chamber may comprise a portion made of a heat conductive material, and the portion made of the heat conductive material may be placed in contact with the heat generating element directly or indirectly.

In place of or in addition to the above embodiment of the present invention, the electronic apparatus may further comprise a heat conductive member, and

the condensation/evaporation chamber may comprise a portion made of a heat conductive material, and the portion made of the heat conductive material is placed in contact with the heat conductive member directly or indirectly.

The heat conductive member may be selected from the group consisting of, for example, a housing of the electronic apparatus, an exterior of a battery, a substrate and a display, but is not limited thereto.

The heat generating element may be selected from the group consisting of, for example, an integrated circuit, a light emitting element, a field effect transistor, a motor, a coil, a converter, an inverter and capacitor, but is not limited thereto.

According to the second aspect of the present invention, there is provided an electronic apparatus comprising:

a first member and a second member; and

a device comprising: a reaction chamber containing a chemical heat storage material which shows an endothermic reaction and an exothermic reaction reversibly; a condensation/evaporation chamber for condensing or evaporating a condensable component produced from the endothermic reaction of the chemical heat storage material; and a communication part which communicates between the reaction chamber and the condensation/evaporation chamber;

wherein the first member is thermally combined with the reaction chamber, and the condensation/evaporation chamber is thermally combined with the second member.

In the electronic apparatus according to the present invention, in a case of increase in a temperature of the first member and/or decrease in a temperature of the second member, heat can be transferred from the first member to the reaction chamber, the chemical heat storage material can produce the condensable component by the endothermic reaction in the reaction chamber, the condensable component can move in a gaseous state from the reaction chamber to the condensation/evaporation chamber through the communication part, the condensable component can be condensed in the condensation/evaporation chamber to generate heat, and the heat can be transferred from the condensation/evaporation chamber to the second member.

Also in the electronic apparatus according to the present invention, in a case of decrease in a temperature of the first member and/or increase in a temperature of the second member, heat can be transferred from the reaction chamber to the first member, the exothermic reaction can occur to use the condensable component in the reaction chamber, the condensable component in a gaseous state can move from the condensation/evaporation chamber to the reaction chamber through the communication part, the condensable component which is condensed in the condensation/evaporation chamber can evaporate by obtaining heat, and the heat can be transferred from the second member to the condensation/evaporation chamber.

The electronic apparatus related to either or both of the first and the second aspects of the present invention preferably has at least one of the following features:

(i) the communication part is provided with a filter allowing gas to path through but not substantially allowing solid and liquid to path through;

(ii) the chemical heat storage material is molded or packed in the reaction chamber, the minimum cross-sectional dimension of the chemical heat storage material which is molded or packed is larger than the minimum cross-sectional dimension of the communication part;

(iii) the condensation/evaporation chamber contains a material which is able to trap liquid, or at least a portion of an inner surface of the condensation/evaporation chamber is made of the material which is able to trap liquid.

According to such features, even when the electronic apparatus is rotated or so in a vertical direction and/or a horizontal direction, it is possible to effectively prevent the chemical heat storage material (generally in a state of solid or semisolid) in the reaction chamber from moving from the reaction chamber to the condensation/evaporation chamber through the communication part (in cases of the features (i) and (ii)), and it is also possible to effectively prevent the condensable component condensed (liquid) in the condensation/evaporation chamber from moving from the condensation/evaporation chamber to the reaction chamber through the communication part (in cases of the features (i) and (iii)), and thereby it becomes possible to effectively prevent the capability of the device as a chemical heat pump from being impaired. The above features and effects obtained thereby address the peculiar problem that solid and liquid matters in the device may move between the two chambers since the electronic apparatus of a mobile type is used rotatably or so in a vertical direction and/or a horizontal direction. The conventional chemical heat pump is intended to be used while being placed or moved toward the horizontal direction. The above described problem in the application of the electronic apparatus have found uniquely by the present inventors (which is also applied to the third aspect of the present invention described hereafter).

According to the third aspect of the present invention, there is provided an electronic apparatus having a function of suppressing temperature rise of a heating generating element, which comprises:

a heat generating element; and

at least one reaction chamber containing a chemical heat storage material,

wherein heat generated from the heat generating element is transferred from an outer surface of the heat generating element to the chemical heat storage material in the at least one reaction chamber, and the chemical heat storage material absorbs the heat by a reaction to suppress the temperature rise of the heat generating element.

In one embodiment related to the third aspect of the present invention, the electronic apparatus comprises a first reaction chamber containing a first chemical heat storage material, and a second reaction chamber containing a second chemical heat storage material,

the first chemical heat storage material and the second chemical heat storage material absorb or produce heat by reactions involving the same component,

the first reaction chamber and the second reaction chamber communicate with each other by a communication part, allowing the said component to move through the communication part,

heat generated by the heat generating element is transferred to either the first chemical heat storage material in the first reaction chamber or the second heat storage material in the second reaction chamber.

In the above embodiment of the present invention, the electronic apparatus may further comprise a condensation/evaporation chamber for condensing or evaporating the said component,

wherein the condensation/evaporation chamber may communicate with the communication part between the first reaction chamber and the second reaction chamber, allowing the said component to move to and from the condensation/evaporation chamber.

Alternatively, in the above embodiment of the present invention, the electronic apparatus may further comprise a condensation/evaporation chamber for condensing or evaporating the said component,

wherein the condensation/evaporation chamber communicates with either the first reaction chamber or the second reaction chamber by another communication part, allowing the said component to move to and from the condensation/evaporation chamber.

The electronic apparatus related to the third aspect of the present invention preferably has at least one of the following features:

(i′) any of the communication part(s) communicating between the chambers (the first reaction chamber, the second reaction chamber and the condensation/evaporation chamber) is provided with a filter allowing gas to path through but not substantially allowing solid and liquid to path through;

(ii′) the first chemical heat storage material is molded or packed in the first reaction chamber, the minimum cross-sectional dimension of the first chemical heat storage material which is molded or packed is larger than the minimum cross-sectional dimension of the communication part (and preferably another communication part, if present), and/or the second chemical heat storage material is molded or packed in the second reaction chamber, the minimum cross-sectional dimension of the second chemical heat storage material which is molded or packed is larger than the minimum cross-sectional dimension of the communication part (and preferably another communication part, if present);

(iii′) the condensation/evaporation chamber contains a material which is able to trap liquid, or at least a portion of an inner surface of the condensation/evaporation chamber is made of the material which is able to trap liquid.

According to such features, even when the electronic apparatus is rotated or so in a vertical direction and/or a horizontal direction, it is possible to effectively prevent the chemical heat storage material (generally in a state of solid or semisolid) in the first and/or second reaction chamber from moving from the first and/or second reaction chamber to the condensation/evaporation chamber through the communication part (in cases of the features (i′) and (ii′)), and it is also possible to effectively prevent the condensable component condensed (liquid) in the condensation/evaporation chamber from moving from the condensation/evaporation chamber to the first and/or second reaction chamber through the communication part (in cases of the features (i′) and (iii′)), and thereby it becomes possible to effectively prevent the capability of a chemical heat pump composed of these members from being impaired.

Throughout all of the aspects of the present invention, the term “a chemical heat storage material” means a substance that is able to store heat by endothermic reaction. In the present invention, the condensable component (a component capable of being condensed or evaporating in the condensation/evaporation chamber) generated from the chemical heat storage material by the endothermic reaction may be water, but not limited thereto. Alternatively, with respect to the third aspect of the present invention, the chemical heat storage material may be one which produces, in place of the condensable component, other component of phase changeable (e.g. sublimation) by the endothermic reaction. In this case, the condensation/evaporation chamber functions as a phase change chamber (e.g. a sublimation chamber) where this component changes its phase.

Such a chemical heat storage material preferably shows an endothermic reaction at a temperature of 30 to 200° C.

Further, throughout all of the aspects of the present invention, it is possible to use, in place of the chemical heat storage material, at least one heat storage material selected form the group consisting of zeolite, silica gel, mesoporous silica and activated carbon. Also in this case, it is possible to bring about effects corresponding to the respective heat storage materials.

According to the first aspect of the present invention, a chemical heat pump (or a device wherein a reaction chamber and a condensation/evaporation chamber communicate with each other by a communication part) is applied to an electronic apparatus having a heat generating element, and uses a chemical heat storage material showing an endothermic reaction by heat generated from the heat generating element, so that it is possible to draw and store heat from the heat generating element by the reaction of the chemical heat storage material when the heat generating element generates the heat, and thereby to suppress the temperature rise of the heat generating element. In other words, it is realized to conduct transfer or leveling of heat at least temporally in the electronic apparatus.

According to the second aspect of the present invention, a chemical heat pump is applied to an electronic apparatus between the first and the second members, and a reaction chamber and a condensation/evaporation chamber of the chemical heat pump are thermally combined with the first and the second members, respectively, so that it is possible to transfer heat from the first member to the second member, or from the second member to the first member while the chemical heat storage material stores or emits the heat. In other words, it is realized to conduct transfer of leveling of heat temporally and spatially in the electronic apparatus.

According to the third aspect of the present invention, a reaction chamber containing a chemical heat storage material is provided to an electronic apparatus having a heat generating element, so that heat generated from the heat generating element is conducted from the outer surface of the heat generating element to the chemical heat storage material contained in the reaction chamber and the chemical heat storage material absorbs (or stores) heat by a reaction, and thereby it is possible to suppress the temperature rise of the heat generating element.

According to any of the aspects of the present invention, it is possible to use a chemical reaction of the chemical heat storage material, and thus to obtain a high capacity of heat storage. Furthermore, when an amount of the heat generated by the heat generating element is decreased or reduced, cold energy (or negative amount of heat) is obtained at the chamber to which the heat generated by the heat generating element is not directly conducted (this chamber is typically a condensation/evaporation chamber, but in a case of the third aspect of the present invention may comprise one of the first reaction chamber and the second reaction chamber to which the heat generated by the heat generating element is not directly conducted). These feathers of obtaining a high capacity of heat storage and cold energy is significant characteristics peculiar to the present invention, compared to a heat pipe using latent heat or a heat transport device using sensible heat. As chemical heat pumps other than a chemical heat pump using a chemical reaction, a mechanical heat pump and a heat pump using an adsorption or absorption reaction are known. According to the present invention, since it uses a chemical reaction of the chemical heat storage material, unlike the mechanical heat pump, the present invention does not require a large mechanical component having a complicated structure, e.g. a compressor, and compared with the case of using an absorption or adsorption reaction, the present invention is able to obtain a higher capacity of heat storage and to store heat in a wider temperature range.

However, the present invention is not limited to those using a chemical heat storage material, but may widely comprise those using other heat storage material such as at least one heat storage material selected from the group consisting of, for example, zeolite, silica gel, mesoporous silica and activated carbon. Also in this case, it is possible to bring about effects corresponding to the respective heat storage materials. Further, compared with the chemical heat storage material, such heat storage material may provide advantages of being easy to handle and of simplifying the structure (for example, it is not necessary to consider prevention of corrosion).

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 shows a schematic cross-sectional view of an electronic apparatus according to one embodiment of the present invention.

FIG. 2 shows a schematic cross-sectional view of an electronic apparatus according to other embodiment of the present invention.

FIGS. 3A to 3C show schematic top views showing various modifications of the electronic apparatus according to other embodiment of the present invention.

FIG. 4 shows a schematic top view showing one CHP-equipped example in Examples of the electronic apparatus of the present invention.

FIG. 5 shows a schematic top view showing other CHP-equipped example in Examples of the electronic apparatus of the present invention.

FIG. 6 shows a schematic top view showing other CHP-equipped example in Examples of the electronic apparatus of the present invention.

FIG. 7 shows a schematic top view showing other CHP-equipped example in Examples of the electronic apparatus of the present invention.

FIG. 8 shows a schematic cross-sectional view showing a model used for simulation in a comparative example of the electronic apparatus of the present invention.

FIG. 9 shows a schematic cross-sectional view showing a model used for simulation in one example of the electronic apparatus of the present invention.

FIGS. 10A and 10B show a graph and a table showing change in temperatures of the reaction chamber and the CPU with the passage of time in the simulation of FIG. 9.

FIG. 11 shows a schematic cross-sectional view showing a model used for simulation in other example of the electronic apparatus of the present invention.

FIGS. 12A to 12D show schematic cross-sectional views each showing an exemplary production process of a CHP to be used in an electronic apparatus in one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

An electronic apparatus in some embodiments of the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto.

First, the configuration of a chemical heat pump (CHP) as a device wherein a condensation/evaporation chamber and a reaction chamber communicate with each other by a communication part will be described below. In the present embodiment, as shown in FIG. 1, a chemical heat pump 10 includes a reaction chamber 1 containing a chemical heat storage material, a condensation/evaporation chamber 3 for condensing or evaporating a condensable component, and a communication part which communicates therebetween. A chemical reaction of the chemical heat storage material is a drive source for transferring heat by the chemical heat pump 10, and the condensable component is a working medium of the chemical heat pump 10.

As the chemical heat storage material, any suitable material may be used as long as it is able to store heat by an endothermic reaction. According to the principles of the chemical heat pump, the chemical heat storage material may show an endothermic reaction and an exothermic reaction which are reversible with each other, and produce the condensable component from any of these reactions, but is not limited thereto. The condensable component is a component which is able to change its phase between a gaseous state (gas phase) and a liquid state (liquid phase) under the environment of use.

In the present embodiment, a chemical heat storage material that produces a condensable component by an endothermic reaction. Such a chemical heat storage material may show a dehydration reaction as the endothermic reaction and show a hydration reaction as the exothermic reaction. In this case, the condensable component is water.

In particular, hydrates of inorganic compounds, inorganic hydroxides and the like may be used for the chemical heat storage material described above. More specifically, examples thereof include hydrates of alkaline earth metal compounds and alkaline earth metal hydroxides, e.g. hydrates of calcium sulfate, calcium chloride and so on, and hydroxides of magnesium, calcium and so on.

For example, calcium sulfate hemihydrate shows an endothermic reaction below:

$\left. {{{{CaSO}_{4} \cdot \frac{1}{2}}H_{2}{O(s)}} + Q_{1}}\rightarrow{{{CaSO}_{4}(s)} + {\frac{1}{2}H_{2}{O(g)}}} \right.$

wherein Q₁ is known as approximately 16.7 kJ/mol.

The endothermic reaction of calcium sulfate hemihydrate may proceed at, for example, about 50 to 150° C., although it depends on the various conditions. This is a reversible reaction, and a reverse reaction with respect to the above described reaction is the exothermic reaction. Calcium sulfate hemihydrate is in a solid state (e.g. powder), calcium sulfate is in a solid state, and water is in a gaseous state.

Further, for example, calcium chloride hydrate shows an endothermic reaction below:

CaCl₂ .nH₂O(s)+Q₂→CaCl₂(s)+nH₂O(g)

wherein n is a number of water molecules for hydration, specifically 1, 2, 4 and 6; Q₂ is known as about 30 to 50 kJ/mol.

The endothermic reaction of calcium chloride hydrate may proceed at, for example, about 30 to 150° C., although it depends on the various conditions. This is a reversible reaction, and a reverse reaction with respect to the above described reaction is the exothermic reaction. Calcium chloride hydrate is in a solid state (e.g. powder), calcium chloride is in a solid state, and water is in a gaseous state.

However, it is not limited to the examples above, any suitable chemical heat storage material (for example, one capable of generating ammonia) may be used and selected appropriately to show an endothermic reaction by heat generated from the heat generating element.

In a broader concept, the chemical heat storage material usable in the present invention is preferably one showing the endothermic reaction at a temperature such as 30 to 200° C., and more preferably one showing the endothermic reaction at a temperature of 40° C. or more, particularly 50° C. or more, and of 150° C. or less, particularly 120° C. or less.

This chemical heat storage material is contained in the reaction chamber 1. The chemical heat storage material may form, for example, a solid phase 2 a, and there may exist a gas phase 2 b containing a condensable component in the reaction chamber 1. It is desirable that the pressure in the reaction chamber is substantially equal to an equilibrium pressure of the exothermic reaction and the endothermic reaction at a general temperature environment for use (when the heat generating element is in a non-heating state).

On the other hand, in the condensation/evaporation chamber 3, there exists a condensable component as being contained in a gas phase 4 a and a liquid phase 4 b. The component which has been condensed beforehand (e.g. water in a liquid state) may be contained in the condensation/evaporation chamber, although the present embodiment is not limited thereto. It is desirable that the pressure in the condensation/evaporation chamber is substantially equal to a saturated vapor pressure of the condensable component (saturated water vapor pressure in the case of water) at a temperature environment for use.

The communication part 5 for communicating (or connecting) between the reaction chamber 1 and the condensation/evaporation chamber 3 is configured so that the condensable component is movable between them. More specifically, the condensable component may move in a gaseous state, and in this case the communication part 5 is configured to pass gas therethrough. Such a communication part may be conveniently a tubular member, but is not limited thereto.

The communication part 5 may or may not have a valve (not shown). If the communication part 5 does not have a valve, the devise has a simple configuration, and the movement of the condensable component and thus the operation of the chemical heat pump 10 depend on the progress of the reaction in the reaction chamber (1) and/or the progress of the phase change in the condensation/evaporation chamber 3 (typically, the temperature in the condensation/evaporation chamber 1 and/or the reaction chamber 1). If the communication part 5 has a valve, the movement of the condensable component and thus the operation of the chemical heat pump 10 is controllable by opening and closing the valve, and it becomes possible to manage the transfer of heat and the timing of heat generation and cooling, and therefore it becomes possible to provide the electronic apparatus with more elaborate thermal design for its inside.

Such chemical heat pump 10 is in a closed system without the entry and exit of substances, but is formed to enable the entry and exit of heat through at least the reaction chamber 1, and preferably the reaction chamber 1 and the condensation/evaporation chamber 3. In particular, the reaction chamber 1 and preferably the condensation/evaporation chamber 3 may be at least partially made of a heat conductive material, respectively. The heat conductive material is not particularly limited but, for example, may be any of good heat conductors such as metals (e.g. copper), oxides (e.g. alumina), nitrides (e.g. aluminum nitride), carbon and so on.

The chemical heat pump 10 used in the electronic apparatus of the present embodiment preferably has any of the following features, either alone or in combination of any two or more:

(i) the communication part 5 is provided with a filter allowing gas to path through but not substantially allowing solid and liquid to path through;

(ii) the chemical heat storage material is molded or packed in the reaction chamber 1, the minimum cross-sectional dimension of the chemical heat storage material which is molded or packed being larger than the minimum cross-sectional dimension of the communication part 5;

(iii) the condensation/evaporation chamber 3 contains a material capable of trapping liquid, or at least a portion of an inner surface of the condensation/evaporation chamber 3 is made of the material capable of trapping liquid.

Regarding the above (i), as the communication part 5 is provided with the filter allowing gas to path through but does substantially allowing solid and liquid to path through, even when the electronic apparatus 20 is rotated or so in a vertical direction and/or a horizontal direction, it is possible to effectively prevent the chemical heat storage material (generally in a state of solid or semisolid) in the reaction chamber 1 from moving from the reaction chamber 1 to the condensation/evaporation chamber 3 through the communication part 5, and it is also possible to effectively prevent the condensable component condensed (liquid) in the condensation/evaporation chamber 3 from moving from the condensation/evaporation chamber 3 to the reaction chamber 1 through the communication part 5.

Such filter shall be capable of passing gas but does not substantially allow passage of solid and liquid therethrough. The words “not substantially allowing solid and liquid to path through” means that it may passes a small amount of solid and liquid to the extent not impairing the performance of the chemical heat pump. The filter is preferably one passing a small amount of liquid but not passing solid, and more preferably one not passing both liquid and solid.

More specifically, the filter preferably has a moisture permeability of 1,000 g/m²/24 h or more, particularly of 10,000 g/m²/24 h (according to JIS L1099, B method, generally B-1 method), and thereby it is possible to reduce sufficiently the pressure loss due to the filter. As to non-passage of solid, it is enough when the chemical heat storage material does not pass through, and may be appropriately selected depending on the size of the chemical heat storage material to be used. As to non-passage of liquid, it is preferable to have a waterproof property of 1,000 mm or more, and particularly 10,000 mm or more (according to JIS L1092, A method).

In particular, for example, it is possible to use a film (fine pore filter) formed by stretching polytetrafluoroethylene, which may also be conjugated with polyurethane polymer according to necessity. Such film is available in the market, for example, under the trade name of “GORE-TEX” (registered trademark). It is also possible to use a water-repellent fiber cloth with a polyurethane coating. Such polyurethane coated cloth is available in the market, for example, under the trade name of “Entrant GII” (registered trademark) XT, etc. from Toray Industries, Inc.

However, the filter is not limited to these examples, and it is possible to apply the filter with any suitable structure having a pore size smaller than a water particle and larger than a water vapor particle/molecule.

As long as the filter is able to pass gas, but does not substantially pass solid and liquid, the filter may be provided in the communication part 5 in any manner. For example, the filter may be placed so as to fill at least a part of the inner space of the communication part 5 (preferably, in the vicinity of the reaction chamber 1), or may be placed so as to cover the opening of the communication part 5 (preferably, the opening at the side of the reaction chamber 1).

Regarding the above (ii), as the chemical heat storage material is molded or packed in the reaction chamber 1 and the minimum cross-sectional dimension of the molded or packed chemical heat storage material is larger than the minimum cross-sectional dimension of the communication part 5, even when the electronic apparatus 20 is rotated or so in a vertical direction and/or a horizontal direction, it is possible to effectively prevent the chemical heat storage material (generally in a state of solid or semisolid) in the reaction chamber 1 from moving from the reaction chamber 1 to the condensation/evaporation chamber 3 through the communication part 5.

The chemical heat storage material in the reaction chamber 1 may be molded or packed in any suitable manner. When the chemical heat storage material is hydrate of an inorganic compound (e.g. hydrate of calcium chloride or calcium sulfate), the inorganic compound is solidified by hydration, so that it can be molded using a mold or the like during solidifying. Further, it is possible to mix the chemical heat storage material with a resin material and a solvent etc. if necessary, and mold the resultant composition by mold pressing or the like (the resin material and, if present, the solvent etc. can be removed away partially, and preferably mostly, during the molding). Otherwise, when the chemical heat storage material is a granular material, the chemical heat storage material can be packed by using a wrapping material having one or more openings of which size is smaller than the particle diameter (e.g. average diameter) of the chemical heat storage material, such as mesh, net, fabric (e.g. woven or nonwoven fabric), film and the like. The wrapping material may be made of, for example, metal, natural or synthetic fibers, a polymer material or the like.

The chemical heat storage material molded or packed as described in the above shall have its minimum cross-sectional dimension which is larger than the minimum cross-sectional dimension of the communication part 5. The minimum cross-sectional dimension of the chemical heat storage material packed or molded means the minimum cross-sectional dimension of the chemical heat storage material packed or molded in any cross-section. The minimum cross-sectional dimension of the communication part 5 means the minimum cross-sectional dimension of the internal space the communication part in any cross-section, and usually refers to the size of the narrowest portion of the communication part 5. In other expressions, this may explained by that when a projected area of the molded or packed chemical heat storage material is at a minimum among those of in any direction of projection, the maximum dimension of the minimum projected area is larger than the minimum cross-sectional dimension of the inner space of the communication part 5 which is perpendicular to the center line of the communication part 5. In summary, it is satisfactory that the molded or packed chemical heat storage material has a dimension so that it is not able to pass through the communication part 5. For example, if an opened size of the opening of the communication part 5 at the side of the reaction chamber 1 (and optionally the opening at the side of the condensation/evaporation chamber 3) is smaller than the minimum cross-sectional dimension of the molded or packed chemical heat storage material, a part between the two openings of the communication part 5 may have a larger size.

The molded or packed chemical heat storage material may be present in the reaction chamber 1. However, for the purpose of prompt and efficient movement of heat, it is preferably placed in contact with a position to which the heat from the heat generating element 11 is transmitted well.

Regarding the above (iii), as the condensation/evaporation chamber 3 contains a material capable of trapping liquid or at least a portion of an inner surface of the condensation/evaporation chamber 3 is made of the material capable of trapping liquid, even when the electronic apparatus 20 is rotated or so in a vertical direction and/or a horizontal direction, it is possible to effectively prevent the condensable component condensed (liquid) in the condensation/evaporation chamber 3 from moving from the condensation/evaporation chamber 3 to the reaction chamber 1 through the communication part 5.

Such material may be one capable of trapping liquid reversibly. In particular, porous materials such as ceramics, zeolites, metals or the like can be used, but is not limited thereto.

The material capable of trapping liquid may be contained in the condensation/evaporation chamber 3 or form a part of the inner surface of the condensation/evaporation chamber 3. In the former case, the material capable of trapping liquid is prepared beforehand and supplied into the condensation/evaporation chamber 3. In the latter case, for example, ceramic or zeolite is synthesized, for example by hydrothermal synthesis, on the inner surface of the wall material of the condensation/evaporation chamber 3 to cover the inner surface. In any case, the material capable of trapping liquid may exist in or on the inner surface of the condensation/evaporation chamber 3. However, for the purpose of prompt and efficient movement of heat, it is preferably placed in contact with a position from which heat is transmitted well to a heat conductive member 13.

The chemical heat pump 10 having such configuration may be prepared exemplarily as follows, but the present embodiment is not limited thereto.

First, referring to FIG. 12A, two metal plates 41 a and 41 b are prepared. These metal plates are made preferably of a corrosion resistant metal such as stainless steel, e.g. SUS, but not limited thereto. The metal plates 41 a and 41 b may have a thickness of, for example, 0.01 mm or more, particularly 0.05 to 0.5 mm. The material and the thickness of the metal plates 41 a and 41 b may be the same as or different from each other.

Next, as shown in FIG. 12B, the one metal plate 41 a is formed with two protruded portions 43 a which correspond to the reaction chamber 1 and the condensation/evaporation chamber 3. The dimensions of the protruded portions 43 a may be determined according to the desired dimensions for the reaction chamber 1 and the condensation/evaporation chamber 3. The height of the protruded portions 43 a may be, for example, 0.1 to 100 mm, particularly 0.3 to 10 mm, and may be the same as or different from each other. On the other hand, the other metal plate 42 b is formed with a recessed portion 43 b which corresponds to the communication part 3. The dimensions of the recessed portion 43 b may be ones which enables that the communication part 3 is formed to communicate between the reaction chamber 1 and the condensation/evaporation chamber 3 and the condensable component is movable through the inside of the communication part 3. The depth of the recessed portion 43 b may be, for example, 0.1 to 100 mm, particularly 0.3 to 10 mm. The formation of the protruded and recessed portions 43 a, 43 b in the metal plates 41 a, 41 b may be conducted by applying any suitable method, for example, spinning, press working, or the like.

Then, the chemical heat storage material 45 is displaced in one of the two protruded portions 43 a of the metal plate 41, which correspond to the reaction chamber 1. The chemical heat storage material 45 is generally in a solid or semisolid state, and may be in the form of, for example, granules, a sheet or the like. The chemical heat storage material 45 is preferably molded or packaged beforehand as describe in the above, although this is not essential.

Further, if required, the material capable of trapping liquid described in the above (e.g. porous material, not shown in the drawings) is displaced in one of the two protruded portions 43 a of the metal plate 41, which correspond to the condensation/evaporation chamber 3. Alternatively, the inner surface of one of the two protruded portions 43 a of the metal plate 41 and corresponding to the condensation/evaporation chamber 3 may be covered by the material capable of trapping liquid as described in the above.

On the other hand, a filter 47 allowing gas to path through but not substantially allowing solid and liquid to path through is preferably displaced in the recessed portion 43 b of the metal plate 41 b, although this is also not essential.

Thereafter, as shown in FIG. 12C, the metal plates 41 a, 41 b are superimposed with each other to form an internal space by the protruded portions 43 a and the recessed portion 43 b together. As a result, the outer peripheral and flat surfaces of the metal plates 41 a, 41 b are in close contact with each other.

Then, as shown in FIG. 12D, the metal plates 41 a, 41 b superimposed with each other are hermetically sealed at the outer peripheral portion 49. The hermetic sealing is preferably conducted under a pressure which is desired for the inside of the chemical heat pump, which is generally a reduced pressure (depending on the chemical heat storage material used therein), for example, 0.1 to 100,000 Pa, particularly 1.0 to 10,000 Pa (absolute pressure). The hermetic sealing may be conducted by applying any suitable method, and the applicable methods are, for example, laser welding, arc welding, resistance welding, gas welding, brazing, and so on. After the hermetic sealing, unnecessary edges of the outer peripheral portion 49 may be optionally removed off by punching operation or the like.

As described in the above, the chemical heat pump 10 can be produced. However, the production method described above is merely exemplary, and the chemical heat pump which is applicable to the present invention can be produced according to any suitable method.

Next, the chemical heat pump 10 having the configuration as described above is incorporated in the electronic apparatus 20 having the heat generating element 11. The electronic apparatus may have at least one electronic component as the heat generating element 11. The electronic apparatus 20 is generally composed so that a housing (or exterior) encloses an electronic circuit board on which at least one electronic component is mounted. The chemical heat pump 10 is provided on such electronic apparatus 20 (more specifically, in the housing thereof). In the present embodiment, the chemical heat pump 10 may be understood as means for suppressing temperature rise of the heat generating element 11 (or cooling the heat generating element).

The heat generating element 11 may be an electronic component wherein a part of the energy input thereto is converted into heat and lost by generating the heat. Examples of the heat generating element 11 includes: integrated circuits (ICs) such as a central processing unit (CPU), a power management IC (PMIC), a power amplifier (PA), a transceiver IC, and a voltage regulator (VR); light emitting elements such as a light emitting diode (LED), an incandescent lamp, and a semiconductor laser; a field effect transistor (FET) and so on, but not limited thereto. In the electronic apparatus 20, at least one heat generating element may be present, but generally there may be two or more heat generating elements.

The reaction chamber 1 of the chemical heat pump 10 described above is thermally combined to the heat generating element 11. For example, the portion made of a heat conductive material of the reaction chamber 1 may be placed in contact directly or indirectly with the heat generating element 11. Thus, heat transfer is attained between the heat generating element 11 and the reaction chamber 1. If two or more heat generating elements are present in the electronic apparatus 20, one or more heat generating element 11 may be thermally combined with the reaction chamber 1.

On the other hand, although this is not essential to the present embodiment, the condensation/evaporation chamber 3 of the chemical heat pump 10 may be placed so as to be thermally combined with any suitable heat conductive member 13 existing in the electronic apparatus 20. The heat conductive member 13 may be one having a temperature lower than the temperature of the heat generating element 11 while the heat generating element 11 generates heat. Examples of the heat conductive member 13 include the housing of the electronic apparatus, an exterior of a battery (e.g. lithium ion battery, alkaline battery, nickel hydride battery), a substrate, a display and so on, but not limited thereto. For example, the portion made of a heat conductive material of the condensation/evaporation chamber 3 may be placed in contact directly or indirectly with the heat conductive member 13. Thus, heat transfer is attained between the condensation/evaporation chamber 3 and the heat conductive member 13. One or more heat conductive member 13 may be thermally combined with the condensation/evaporation chamber 3.

In the present invention, two members “thermally combined” with each other mean that they are combined so as to enable heat to transfer between them. The thermal combination may be realized by heat conduction through a direct or indirect contact, by thermal radiation with no contact, or by using a heat medium or a heat conductive member. When two members are indirectly in contact with each other in order to be thermally combined, they are preferably in contact with each other by using an adhesive layer of heat conductive (e.g. a layer obtained by using an adhesive of which thermal conductivity is increased by a metal filler or the like), a member made of a heat conductive material (e.g. a heat transfer plate made of a metal, a thermal sheet) or the like.

The electronic apparatus 20 of the present embodiment configured as described above may be used in the following two modes.

First Mode (Heat Storage Process)

First, when the heat generating element 11 starts to generate heat by energy input thereto and causes temperature rise of the heat generating element 11, the heat is transferred to the reaction chamber 1 which is thermally combined with the heat generating element 11. Specifically, the heat generated by the heat generating element 11 is transferred from the outer surface of the heat generating element 11 to the chemical heat storage material contained in the reaction chamber 1 through, for example, the portion made of a heat conductive material of the reaction chamber 1. When the heat is supplied to the reaction chamber in this manner, the endothermic reaction of the chemical heat storage material (heat storage) proceeds in the reaction chamber to produce the condensable component (i.e. a partial pressure of the condensable component in the reaction chamber is increased). As a result, an amount of the heat is taken away from the heat generating element, and thereby the rise in the temperature of the heat generating element is suppressed (typically, the temperature of the outer surface of the heat generating element, which shall apply hereafter).

The condensable component produced in the reaction chamber in this way moves from the reaction chamber 1 to the condensation/evaporation chamber 3 through the communication part 5 in a gas state (vapor). Such movement may occur naturally by diffusion phenomenon, but is not limited thereto. When the communication part 5 is provided with a valve, it is possible to control the movement of the condensable component by opening and closing the valve.

In the condensation/evaporation chamber 3, the condensable component is condensed to generate heat (latent heat). For example, in the case in which the condensable component is water, water in a gas state is phase changed into water in a liquid state according to the following reaction:

$\left. {\frac{1}{2}H_{2}{O(g)}}\rightarrow{{\frac{1}{2}H_{2}{O(l)}} + Q_{3}} \right.$

wherein Q₃ is known as 20.9 kJ/mol.

The temperature in the condensation/evaporation chamber may rise due to the heat generated. In this case, the pressure in the condensation/evaporation chamber is preferably made equal to a saturated vapor pressure of the condensable component beforehand (at a non-heat generating condition) so that the condensable component is in a state of vapor-liquid equilibrium (at a temperature, for example, which is appropriately selected for the heat conductive member 13 when the heat conductive member 13 is placed to be thermally combined with the condensation/evaporation chamber 3), which makes condensation proceed so rapidly.

Then, although it is not essential to the present embodiment, in the case of the condensation/evaporation chamber 3 being thermally combined with the heat conductive member 13, the heat generated in the condensation/evaporation chamber 3 is transferred to the heat conductive member 13 through, for example, the portion made of a heat conductive material of the condensation/evaporation chamber.

As described above, according to the first mode, it is possible to suppress the temperature rise of the heat generating element 11 (or cool the heat generating element) by utilizing the endothermic reaction (heat storage) of the chemical heat storage material. Further, in the case of the condensation/evaporation chamber 3 being thermally combined with a housing of the electronic apparatus 20 as the heat conductive member 13, by storing heat with the chemical heat storage material and assuring that an amount of the heat flowing to the heat conductive member 13 from the condensation/evaporation chamber 3 is smaller than an amount of the heat entering into the reaction camber 1 from the heat generating element 11 (converting a temperature level), it is possible to retain the temperature of the housing at a relatively low temperature. Thus, it becomes possible to control the temperature of the heat generating element 11, and therefore the temperature of the electronic apparatus 20 as a whole.

In the case of the condensation/evaporation chamber 3 being thermally combined with the heat conductive member 13, by reducing the temperature of the heat conductive member 13, it is also possible to attain similar effects (mechanism) to those described above, and it is possible to remove heat from the heat generating element 11, thus suppress the temperature rise of the heat generating element 11, and furthermore to reduce its temperature. In the present embodiment, the heat generating element 11 and the heat conductive member 13 can be understood as the first member thermally combined with the reaction chamber and the second member thermally combined with the condensation/evaporation chamber 3, respectively. However, the first member and the second member are not limited thereto, but may be thermally designed by applying any suitable members.

Second Mode (Heat Release Process)

Then, when the temperature of the heat generating element 11 is decreased by, for example, stopping or reducing the energy input to the heat generating element 11, heat is transferred to the heat generating element 11 from the reaction chamber 1 which is thermally combined therewith. Specifically, the heat is transferred from the system in the reaction chamber 1 to the heat generating element 11 through, for example, the portion made of a heat conductive material of the reaction chamber 1. When the heat is taken away from the system in the reaction chamber 1 in this manner, the exothermic reaction of the chemical heat storage material (heat release), which is a reverse reaction to the endothermic reaction described above, proceeds in the reaction chamber 1 to consume the condensable component (i.e. the partial pressure of the condensable component in the reaction chamber is decreased). As a result, the temperature of the heat generating element 11 shifts to increase.

When the condensable component are consumed in the reaction chamber 1 in this manner, the condensable component moves from the condensation/evaporation chamber 3 to the reaction chamber 1 through the communication part 5 in a gas state (vapor). Such movement may also occur naturally by diffusion phenomenon, but is not limited thereto. When the communication part 5 is provided with a valve, it is possible to control the movement of the condensable component by opening and closing the valve.

In the condensation/evaporation chamber 3, the condensable component in a liquid phase is evaporated by obtaining heat (latent heat). The temperature in the condensation/evaporation chamber 3 may be decreased by being deprived of heat.

Then, although it is not essential to the present embodiment, in the case of the condensation/evaporation chamber 3 being thermally combined with the heat conductive member 13, heat is transferred from the heat conductive member 13 to the condensation/evaporation chamber 3 through, for example, the portion made of a heat conductive material of the condensation/evaporation chamber 3. In other words, it is possible to obtain cold energy from the condensation/evaporation chamber 3 to the heat conductive member 13.

As described above, according to the second mode, it is possible to suppress the temperature decrease of the heat generating element 11 by utilizing the exothermic reaction (heat release) of the chemical heat storage material. Further, in the case of the condensation/evaporation chamber 3 being thermally combined with a housing of the electronic apparatus 20 or an exterior of a battery as the heat conductive member 13, it is also possible to decrease the temperature of the housing or the battery (or cool the housing or the battery). Thus, it becomes possible to control the temperature of the heat generating element 11, and therefore the temperature of the electronic apparatus 20 as a whole.

In the case of the condensation/evaporation chamber 3 being thermally combined with the heat conductive member 13, by raising the temperature of the heat conductive member 13, it is also possible to attain similar effects (mechanism) to those described above, and it is possible to increase the temperature of the heat generating element 11. In the present embodiment, the heat generating element 11 and the heat conductive member 13 can be understood as the first member thermally combined with the reaction chamber and the second member thermally combined with the condensation/evaporation chamber, respectively. However, the first member and the second member are not limited thereto, but may be thermally designed by applying any suitable member. For example, it is also possible to suppress the temperature rise of the second member (or cool the second member) by the second mode.

As can be understood from the above, differently from the conventional method using a cooling fan for heat dissipation, the electronic apparatus of the present invention does not require additional energy input for the purpose of suppressing the temperature rise of the heat generating element, so that the electronic apparatus showing superior energy efficiency is realized.

Also, differently from the conventional method using a cooling fan for heat dissipation, the electronic apparatus of the present invention does not dissipate heat by convection (not exhaust out by generating gas stream), so that the housing of the electronic apparatus may be in a sealed condition (closed system).

Further, compared with the conventional method using a heat pipe for heat dissipation, since the electronic apparatus of the present invention stores heat with the chemical heat storage material, it is possible to obtain a high capacity of heat storage and to obtain a high ability of heat dissipation. Further, in the case of the condensation/evaporation chamber being thermally combined with the heat conductive member, in the first mode described above (heat storage process) an amount of the heat flowing to the heat conductive member from the condensation/evaporation chamber can be smaller than an amount of the heat entering into the reaction camber from the heat generating element (a temperature level can be converted), and in the second mode descried above (heat release process) cold energy can be obtained for the heat conductive member. Thus, by using the housing of the electronic apparatus as the heat conductive member thermally combined with the condensation/evaporation chamber, it is possible to retain the temperature of the housing at a relatively low temperature (for example, the surface temperature of 55° C. or less) and to reduce the adverse effects due to the temperature on other element(s) in the housing (e.g. lithium ion battery). Further, by using the exterior of the battery as the heat conductive member thermally combined with the condensation/evaporation chamber, it is possible to extend life of the battery (e.g. lithium ion battery, which would have a problem of the lowered battery capacity due to a high environmental temperature for use). Further, by using the substrate as the heat conductive member thermally combined with the condensation/evaporation chamber, it is possible to prevent a reliability of the other electronic element(s) mounted on the substrate from impairing.

In addition, according to the electronic apparatus of the present invention, the first member thermally combined with the reaction chamber and the second member thermally combined with the condensation/evaporation chamber can be thermally designed by applying any suitable members, so that it becomes possible to provide the electronic element(s) with a thermally optimal layout depending on the detailed specifications of the electronic apparatus.

In the above, the electronic apparatus in one embodiment of the present invention has described in detail, but the electronic apparatus of the present invention is not limited to such embodiment and may be made with various modifications based on the basic concept of the present invention.

For example, the number of the chemical heat pump(s) installed in the electronic apparatus, the number of the chemical heat pump(s) used for one heat generating element, the number, and the arrangement and so on of the reaction chamber(s), the condensation/evaporation chamber(s) and the communication part(s) present in one chemical heat pump can be appropriately selected.

Also, for example, the condensation/evaporation chamber may be surrounded by an ambient atmosphere in the housing (e.g. so-called air insulation). Alternatively, the condensation/evaporation chamber does not have the portion made of a heat conductive material and is composed of a material showing a low heat conductivity or heat insulation. Further, the condensation/evaporation chamber itself may be eliminated, and also in this case, it is possible to some extent to suppress the temperature rise of the heat generating element by the endothermic reaction of the chemical heat storage material.

That is, as shown in FIG. 2, the electronic apparatus 21 in other embodiment of the present invention includes essentially the heat generating element 11 and at least one reaction chamber 1 containing a chemical heat storage material (which may form a solid phase 2 a). In this case, heat generated by the heat generating element 11 is transferred from the outer surface of the heat generating element 11 to the chemical heat storage material contained in the at least one reaction chamber 1, and the chemical heat storage material absorbs the heat by a reaction, and thereby it is possible to suppress the temperature rise of the heat generating element 11. As long as the heat generating element 11 is thermally combined with the reaction chamber 1, the heat generating element 11 may be placed in any manner.

There may be present two reaction chambers in the electronic apparatus in such other embodiment. More specifically, as shown in FIG. 3A, in the electronic apparatus 22, there may be present the first reaction chamber 1 a containing the first chemical heat storage material and the second reaction chamber 1 b containing the second chemical heat storage material. The first chemical heat storage material and the second chemical heat storage material may absorb or produce heat by any reactions involving the same component (component functioning as a working medium, for example, a condensable component, but not limited thereto, and may be any component which is able to exists in a gas state). The first chemical heat storage material and the second chemical heat storage material may have vapor-liquid equilibrium states which are different from each other. The first chemical heat storage material and the second chemical heat storage material may be selected from those exemplified for the chemical heat storage material in the above, and for example, one of the first chemical heat storage material and the second chemical heat storage material may be calcium sulfate hemihydrate, and the other may be calcium chloride hydrate, and water as the same component described above is involved in their reversible reactions for absorbing and producing heat, but not limited thereto. The first reaction chamber 1 a and the second reaction chamber 1 b communicate with each other by a communication part 5 a therebetween to allow the component (working medium) to move, and heat generated by the heat generating element (not shown) may be transferred to either the first chemical heat storage material in the first reaction chamber 1 a or the second chemical storage material in the second reaction chamber 1 b. As long as the heat generated by the heat generating element (not shown) may be transferred to either the first reaction chamber 1 a or the second reaction chamber 1 b selectively or switchably, an arrangement of the heat generating element, the first reaction chamber 1 a and the second reaction chamber 1 b is not particularly limited.

Further, as an electronic apparatus 23 shown in FIG. 3B, it may further include a condensation/evaporation chamber 3 a for condensing or evaporating the movable component described above, and the condensation/evaporation chamber 3 a communicates with the communication part 5 a between the first reaction chamber 1 a and the second reaction chamber 1 b through a communication part 5 b. This arrangement of the condensation/evaporation chamber 3 a is a parallel arrangement with respect to two reaction chambers 1 a and 1 b.

Alternatively, as an electronic apparatus 24 shown in FIG. 3C, it may further include a condensation/evaporation chamber 3 b for condensing or evaporating the movable component described above, and the condensation/evaporation chamber 3 b communicates with either the first reaction chamber 1 a or the second reaction chamber 1 b (with the second reaction chamber 1 b in FIG. 3C) through another communication part 5 c. This arrangement of the condensation/evaporation chamber 3 b is a series arrangement with respect to two reaction chambers 1 a and 1 b.

In examples of FIGS. 3B and 3C, the movable component corresponds to the condensable component (i.e. a component which is able to change its phase between a gaseous state (gas phase) and a liquid state (liquid phase)), but are not limited thereto. For example, the movable component may be a component which is able to change its phase between a gaseous state (gas phase) and a solid state (solid phase), and in this case the condensation/evaporation chambers 3 a and 3 b are understood as a sublimation chamber.

FIGS. 3A to 3C are intended to exemplary illustrate other embodiment of the present invention, the number of the reaction chambers, and the number of the condensation/evaporation chamber(s) and the sublimation chamber(s) if present, and an arrangement thereof can be appropriately selected.

As to the electronic apparatus in such other embodiment of the present invention, similar descriptions to those in the embodiment described above are also applicable unless otherwise noted.

For example, the electronic apparatus of other embodiment shown in FIGS. 3A to 3C preferably has any of the following features, either alone or in combination of any two or more:

(i′) any of the communication parts 5 a, 5 b, 5 c connecting between the reaction chamber 1 a and the second reaction chamber 1 b and the condensation/evaporation chamber 3 a or 3 b (preferably the communication parts 5 b, 5 c at the side of the condensation/evaporation chamber) is provided with a filter allowing gas to path through but not substantially allowing solid and liquid to path through;

(ii′) the first chemical heat storage material is molded or packed in the first reaction chamber 1 a, the minimum cross-sectional dimension of the first chemical heat storage material which is molded or packed being larger than the minimum cross-sectional dimension of the communication part 5 a; and/or the second chemical heat storage material is molded or packed in the second reaction chamber 1 b, the minimum cross-sectional dimension of the second chemical heat storage material which is molded or packed being larger than the minimum cross-sectional dimension of the communication part 5 a (and preferably another communication part 5 c, if present);

(iii′) the condensation/evaporation chambers 3 a, 3 b contain a material capable of trapping liquid, or at least a portion of an inner surface of the condensation/evaporation chambers 3 a, 3 b is made of the material capable of trapping liquid.

As to these features, similar descriptions to those in the embodiment described above with reference to FIG. 1 and FIGS. 12A to 12D are also applicable, and the similar effects can be obtained.

In the above, the electronic apparatus in some embodiments of the present invention has described, but all of these may be made with further modifications.

That is, the electronic apparatuses in the embodiments described above are all uses the chemical heat storage material, but instead of this, other heat storage material which is able to generate a phase changeable component in association with an endothermic phenomenon may be used. In this case, the phase changeable component is a working medium of the device, this component can move from the reaction chamber in a gaseous state, and the condensation/evaporation chamber or the sublimation chamber described above is understood as a chamber where this component changes its phase (i.e. phase change chamber), which may function as a condensation/evaporation chamber and/or a sublimation chamber.

Such other heat storage material may be appropriately selected (for example, so as to show the endothermic phenomenon by heat generated by the heat generating element) depending on applications of the electronic apparatus of the present invention. Similarly to the chemical heat storage material, such other heat storage material is preferably one showing the endothermic phenomenon at a temperature such as 30 to 200° C., and more preferably one showing the endothermic reaction at a temperature of 40° C. or more, particularly 50° C. or more, and of 150° C. or less, particularly 120° C. or less.

As said other heat storage material which may be used in the present invention, for example, at least one heat storage material selected form the group consisting of, for example, zeolite, silica gel, mesoporous silica and activated carbon may be used (hereinafter, these are simply referred to as “zeolite, etc.”). All of them are able to reversibly adsorb and desorb, for example, water (or hydration or dehydration, which shall apply hereafter), and show an endothermic phenomenon on desorption of water:

Z.xH₂O(s)+Q₄→Z(s)+xH₂O(g)

wherein Z represents the composition of the zeolite etc., and x may be a variously changeable value depending on the composition. Although it depends on the specific composition, Q₄ is about 30 to 80 kJ/mol in the case of zeolite. This desorption of water, depending on the various conditions, but may proceed at, for example, about 50 to 150° C. for zeolite, about 5 to 150° C. for silica gel, about 5 to 150° C. for mesoporous silica, and about 5 to 150° C. with activated carbon.

Zeolite means crystalline, hydrated aluminosilicates having a basic skeleton of so-called zeolite structure, that is, a three-dimensional network structure composed of SiO₄ tetrahedra and AlO₄ tetrahedra which are linked by sharing apical oxygen atoms. In general, zeolite can be represented by the following general formula:

(M¹,M² _(1/2))_(m)(Al_(m)Si_(n)O_(2(m+n))).xH₂O(n≧m)

wherein M¹ is a monovalent cation such as Li⁺, Na⁺, and K⁺, M² is a divalent cation such as Ca²⁺, Mg²⁺, and Ba²⁺.

Among them, zeolites which may be suitably used in the present invention are A-type zeolite (LTA), X-type zeolite (FAU), Y-type zeolite (FAU), beta-type zeolite (BEA), ALPO-5 (AFI), and so on.

Silica gel is a three-dimensional structure of colloidal silica, of which porous material properties can be controlled in a wide range, e.g. pore size from several nanometers to several tens of nanometers and specific surface area from 5 to 1000 m²/g. In addition, the surface of primary particles of silica gel is covered by silanol, so that it selectively adsorbs polar molecules (e.g. water) under the influence of silanol.

Mesoporous silica is a substance of silicon dioxide having uniform and regular pores, of which pore size is about 2 to 10 nm.

Activated carbon is means “porous, carbonaceous matter having pores” which have a large specific surface area and adsorption capacity. Its basic skeleton is a planar structure of a two-dimensional lattice of carbon atoms connected each other by an angle of 120°. As such two-dimensional lattices are stacked irregularly to form a crystal lattice, and the crystal lattices are linked randomly to form active carbon. Voids between the crystal lattices are pores of the activated carbon, and water is adsorbed in the pores.

In advance of the preparation of the electronic apparatus of the present invention, the zeolite, etc. are preferably made adsorbed water sufficiently.

When the zeolite etc. are used as said other heat storage material in the electronic apparatus of the present invention, water as the condensable component is the working medium, and therefore it is possible to attain similar effects by similar mechanism to those in the above described embodiments using the chemical heat storage material (which produces water as the condensable component and uses it as the working medium).

An electronic apparatus of the present invention can be suitably used as mobile electronic devices such as smartphones, cellular phones, tablet devices, laptop computers, portable game machines, portable music players, digital cameras, and so on.

EXAMPLES CHP-Equipped Examples

Chemical heat pump (CHP) equipped examples which apply various elements/members as the first member/heat generating element 11 and the second member/heat conductive member 13 in an electronic apparatus of the present invention will be described below in detail with reference to the accompanying drawings, but the present invention is not limited thereto.

(CHP-Equipped Example 1)

Referring to FIG. 4, in this CHP-equipped example, the electronic apparatus is a laptop PC (personal computer) 20 a, and the heat generating element is a CPU 11 a. A chemical heat pump includes a reaction chamber 1, a condensation/evaporation chamber 3, and a communication part 5 for communicating therebetween. The reaction chamber 1 is thermally combined with the CPU 11 a. For example, by using an adhesive of which thermal conductivity is increased with a metal filler, the reaction chamber 1 may be adhered to the CPU 11 a, but is not limited thereto. The condensation/evaporation chamber 3 is not thermally combined with a lithium ion battery 13 a and a housing 13 b and is thermally insulated by air. The condensation/evaporation chamber 3 is preferably thermally insulated from the CPU 11 a (the heat generating element).

In this CHP-equipped example, when the CPU 11 a is operated and generates heat to reach a relatively high temperature (which depends on the chemical heat storage material to be used), an endothermic reaction of the chemical heat storage material in the reaction chamber 1 proceeds by drawing heat from the CPU 11 a (the condensable component generated during the reaction may be condensed in the condensation/evaporation chamber 3), thereby reducing the temperature rise of the CPU 11 a, preferably to stabilize the temperature of the CPU 11 a, and thus to maintain the temperature of the CPU 11 a not exceeding the upper temperature limit. Thereafter, the operation of the CPU 11 a is changed to a lower level or stopped and the temperature of the CPU 11 a is decreased to a relatively lower temperature, an exothermic reaction of the chemical heat storage material in the reaction chamber 1 proceeds to provide heat to the CPU 11 a (at this time, the condensable component may be evaporated in the condensation/evaporation chamber 3), and thus the temperature of the CPU 11 a may rise slightly. That is, the chemical heat pump draws heat from the CPU 11 a during the high temperature operation of the CPU 11 a, and provides heat to the CPU 11 a during the low temperature operation.

(CHP-Equipped Example 2)

Referring to FIG. 5, in this CHP-equipped example, the electronic apparatus is a laptop PC 20 a, and the heat generating element is a CPU 11 a. A chemical heat pump 10 includes a reaction chamber 1, a condensation/evaporation chamber 3, and a communication part 5 for communicating therebetween. The reaction chamber 1 is thermally combined with the CPU 11 a. The condensation/evaporation chamber 3 is thermally combined with a housing 13 b. For example, by using an adhesive of which thermal conductivity is increased with a metal filler, the reaction chamber 1 and the condensation/evaporation chamber 3 may be adhered to the CPU 11 a and the housing 13 b respectively, but are not limited thereto.

In this CHP-equipped example, when the CPU 11 a is operated and generates heat to reach a relatively high temperature (which depends on the chemical heat storage material to be used), an endothermic reaction of the chemical heat storage material in the reaction chamber 1 proceeds by drawing heat from the CPU 11 a, and the condensable component generated by the endothermic reaction is condensed in the condensation/evaporation chamber 3 to provide heat to the housing 13 b, thereby reducing the temperature rise of the CPU 11 a, preferably to stabilize the temperature of the CPU 11 a, and thus to maintain the temperature of the CPU 11 a not exceeding the upper temperature limit (e.g. 120° C. or less). Thereafter, the operation of the CPU 11 a is changed to a lower level or stopped and the temperature of the CPU 11 a is decreased to a relatively lower temperature, an exothermic reaction of the chemical heat storage material in the reaction chamber 1 proceeds and the condensable component in the condensation/evaporation chamber 3 evaporates by drawing heat from the housing 13 b, and thus the temperature of the CPU 11 a rises slightly and the temperature of the housing 13 b is decreased and can be retained at a relatively lower temperature (e.g. 55° C. or less). That is, the chemical heat pump 10 draws heat from the CPU 11 a and transfer heat to the housing 13 b during the high temperature operation of the CPU 11 a, and provides heat to the CPU 11 a and draws heat from (cools) the housing 13 b during the low temperature operation.

(CHP-Equipped Example 3)

Referring to FIG. 6, in this CHP-equipped example, the electronic apparatus is a smartphone 20 b, and the heat generating element is a power management IC 11 b. A chemical heat pump 10 includes a reaction chamber 1, a condensation/evaporation chamber 3, and a communication part 5 for communicating therebetween. The reaction chamber 1 is thermally combined with the power management IC 11 b. The condensation/evaporation chamber 3 is thermally combined with a lithium ion battery 13 a. For example, by using an adhesive of which thermal conductivity is increased with a metal filler, the reaction chamber 1 and the condensation/evaporation chamber 3 may be adhered to the power management IC 11 b and the lithium ion battery 13 a respectively, but are not limited thereto.

In this CHP-equipped example, when the power management IC 11 b is operated and generates heat to reach a relatively high temperature (which depends on the chemical heat storage material to be used), an endothermic reaction of the chemical heat storage material in the reaction chamber 1 proceeds by drawing heat from the power management IC 11 b, and the condensable component generated by the endothermic reaction is condensed in the condensation/evaporation chamber 3 to provide heat to the lithium ion battery 13 a, thereby reducing the temperature rise of the power management IC 11 b, preferably to stabilize the temperature of the power management IC 11 b, and thus to maintain the temperature of the power management IC 11 b not exceeding the upper temperature limit (e.g. 85° C. or less). Thereafter, the operation of the power management IC 11 b is changed to a lower level or stopped and the temperature of the power management IC 11 b is decreased to a relatively lower temperature, an exothermic reaction of the chemical heat storage material in the reaction chamber 1 proceeds and the condensable component in the condensation/evaporation chamber 3 evaporates by drawing heat from the lithium ion battery 13 a, and thus the temperature of the power management IC 11 b rises slightly and the temperature of the lithium ion battery 13 a is decreased and can be retained at/within a temperature which does not cause the problem of a shorter lifetime of lithium ion battery 13 a (e.g. 40° C. or less). That is, the chemical heat pump 10 draws heat from the power management IC 11 b and transfer heat to the lithium ion battery 13 a during the high temperature operation of the power management IC 11 b, and provides heat to the power management IC 11 b and draws heat from (cools) the lithium ion battery 13 a during the low temperature operation.

(CHP-Equipped Example 4)

Referring to FIG. 7, in this CHP-equipped example, the electronic apparatus is a smartphone 20 b, and the heat generating elements are two power amplifiers 11 c and 11 c′. The first chemical heat pump 10 includes a reaction chamber 1, a condensation/evaporation chamber 3, and a communication part 5 for communicating therebetween. The second chemical heat pump 10′ includes a reaction chamber 1′, a condensation/evaporation chamber 3′, and a communication part 5′ for communicating therebetween. The reaction chamber 1 is thermally combined with the power amplifier 11 c. The reaction chamber 1′ is thermally combined with the power amplifier 11 c′. The condensation/evaporation chambers 3 and 3′ are thermally combined with a housing 13 b. For example, by using an adhesive of which thermal conductivity is increased with a metal filler, the reaction chamber 1 and the condensation/evaporation chamber 3 may be adhered to the power amplifier 11 c and the housing 13 b respectively, and the reaction chamber 1′ and the condensation/evaporation chamber 3′ may be adhered to the power amplifier 11 c′ and the housing 13 b respectively, but are not limited thereto.

In this CHP-equipped example, when the power amplifier 11 c is operated during the use of Band 1 and generates heat to reach a relatively high temperature (which depends on the chemical heat storage material to be used), an endothermic reaction of the chemical heat storage material in the reaction chamber 1 proceeds by drawing heat from the power amplifier 11 c, and the condensable component generated by the endothermic reaction is condensed in the condensation/evaporation chamber 3 to provide heat to the housing 13 b, thereby reducing the temperature rise of the power amplifier 11 c, preferably to stabilize the temperature of the power amplifier 11 c, and thus to maintain the temperature of the power amplifier 11 c not exceeding the upper temperature limit (e.g. 85° C. or less). Thereafter, switching from Band 1 to Band 2, the operation of the power amplifier 11 is stopped and the power amplifier 11 c′ is made operated. Then, the power amplifier 11 c′ is operated and generates heat to reach a relatively high temperature (which depends on the chemical heat storage material to be used), an endothermic reaction of the chemical heat storage material in the reaction chamber 1′ proceeds by drawing heat from the power amplifier 11 c′, and the condensable component generated by the endothermic reaction is condensed in the condensation/evaporation chamber 3′ to provide heat to the housing 13 b, thereby reducing the temperature rise of the power amplifier 11 c′, preferably to stabilize the temperature of the power amplifier 11 c′, and thus to maintain the temperature of the power amplifier 11 c′ not exceeding the upper temperature limit (e.g. 85° C. or less). On the other hand, the temperature of the power amplifier 11 c is decreased to a relatively lower temperature, and an exothermic reaction of the chemical heat storage material in the reaction chamber 1 proceeds and the condensable component in the condensation/evaporation chamber 3 evaporates by drawing heat from the housing 13 b, and thus the temperature of the power amplifier 11 c rises slightly and the temperature of the housing 13 b is decreased. Therefore, the housing 13 b can be retained at a relatively lower temperature (e.g. 55° C. or less). That is, by the switchable use between Band 1 and Band 2, the chemical heat pumps 10 and 10′ draw heat from the power amplifier 11 c or 11 c′ at the higher temperature operation and transfer heat to the power amplifier 11 c or 11 c′ at the stopped operation, and thereby it becomes possible to control the heat transfer to and from the housing 13 b.

Simulations

Next, simulations of heat balance were conducted based on some models.

(Simulation Model 1)

Based on a model representing the structure of an existing smartphone, firstly, validity of an analytical method used for simulations (including various conditions) was verified in the case of CPU heat generation amount of 1.8 W (which corresponds to the actually measured amount of generated heat), and then according to this analytical method, simulation was conducted for the case of CPU heat generation amount of 7 W as a comparative example.

As shown in FIG. 8, this simulation model assumes an electronic apparatus model 30 wherein an electronic circuit board 22 mounting a CPU 21 a and a power management IC (PMIC) 21 b respectively on its upper and lower surfaces, a battery 24, and a camera unit 25 are housed in a space between a chassis (upper heat conductive member) 23 a and a battery cover (lower heat conductive member) 23 b, and a display 26 is placed on the upper surface of the chassis 23 a. The camera unit 25 is in contact with the electronic circuit board 22, the chassis 23 a and the battery cover 23 b. The battery 24 is in contact with the chassis 23 a and the battery cover 23 b. The electronic circuit board 22 is not contact with the battery 24, but in contact with the battery cover 23 b (contacting part is not shown). The chassis 23 a is in contact with the display 26, and the display 26 is exposed to an ambient atmosphere (air) 29. A portion of the battery cover 23 b is in contact with a human body 28, and the rest thereof is exposed to the ambient atmosphere (air) 29. The imaginary routes for allowing heat to move in and out in this electronic apparatus model 30 are shown by double arrows in FIG. 8.

The dimensions and the heat generation amount for each of the above described members in the electronic apparatus model 30 were set as shown in Table 1 below (in Table 1, the symbol “-” means that the heat generation amount is zero). Among these members, the CPU 21 a and the PMIC 21 b are heat generating elements, the camera unit 25 and the battery 24 are also heat generating elements but their amounts of heat generation is very small compared to the CPU 21 a and the PMIC 21 b.

TABLE 1 Dimensions Heat Member (Reference signs in Length Width Height generation the Drawings) (mm) (mm) (mm) amount (W) Display (26) 82.2 54.8 2.14 — Chassis (23a) 115.7 58.5 1.5 — Electronic circuit board (22) 96.5 41.3 0.8 — Camera unit (25) 8.9 9.2 7.2 0.2 Battery (24) 81.4 31.5 4.3 0.2 Battery cover (23b) 115 58 1.5 — CPU (21a) 16.5 14 0.8 1.8 or 7 PMIC (21b) 7.4 5.8 0.5 0.8

With respect to these members, values of physical properties such as density, specific heat, thermal conductivity, etc. were appropriately set to correspond to each of members used in an existing smartphone, and mc value (a product of specific heat and mass) was calculated for them and used. The specific heat and the density were assumed to be constant regardless of the temperature.

Initial and boundary conditions in the simulation were as follows.

Initial Conditions:

A temperature of the ambient atmosphere (air) 29 was constant at a temperature of 25° C.

All of the members were at a temperature of 25° C.

Boundary Condition:

The CPU 21 a, the PMIC 21 b, the camera unit 25, and the battery 24 were intended to start heat generation at t=0 (the start time of heat generation was set at t=0).

The human body 28 was constant at a temperature of 36° C., and at t=0, one third of the exposed surface of the battery cover 23 b came in contact (heat transfer) with the human body 28, and the remaining two third was exposed to the ambient atmosphere (air) 29.

Heat transfer between the display 26, the battery cover 23 b and the ambient atmosphere (air) 29 was obtained by convection heat transfer and radiation heat transfer.

Other heat transfer was obtained by conduction heat transfer, unless otherwise noted.

In the Case of CPU Heat Generation Amount of 1.8 W (Validation of the Analytical Method)

The amount of heat generation by a CPU used in an existing smartphone was measured as about 1.8 W.

Therefore, first, setting the heat generation amount of the CPU 21 a in the electronic apparatus model 30 at 1.8 W, simulation of heat balance was conducted by applying the analytical method comprising the various conditions/assumptions described above. As the results of this simulation, there were shown that: the temperature of the CPU 21 a increased to about 50° C. at t=about 100 seconds, reached to about 60° C. at t=about 1,000 seconds, and became in a quasi-steady state; and the temperature of the battery cover 23 b increased to about 40° C. at t=about 1,000 seconds and became in a quasi-steady state.

On the other hand, the existing smartphone was used under the similar conditions (in the ambient atmosphere of 25° C., and one third of the exposed surface of the battery cover 23 b was made contact with the human body having a body temperature of about 36° C.), and the temperatures of the CPU and the battery cover, etc. were actually measured. The measured temperatures of the CPU and the battery cover in the quasi-steady states were 62° C. and 39° C. respectively, and they were almost same as the simulated values described in the above.

Therefore, the analytical method applied in this simulation was proved to be appropriate.

In the Case of CPU Heat Generation Amount of 7 W Comparative Example

Setting the heat generation amount of the CPU 21 a of the electronic apparatus model 30 as unknown value, and the simulation was conducted by applying the analytical method comprising the various conditions/assumptions described above, resulting in that the heat generation amount of the CPU 21 a at a point showing the temperature of the CPU 21 a at 130° C. in quasi-steady state was calculated to be 7 W. The condition for a heat generation amount of CPU at 7 W is too severe to be supposed under normal conditions for use of CPUs.

Then, assuming the heat generation amount of the CPU 21 a in the electronic apparatus model 30 at 7 W, simulation of heat balance was conducted by applying the analytical method comprising the various conditions/assumptions described above. As the results of this simulation, there were shown that: the temperature of the CPU 21 a increased to about 100° C. at t=about 100 seconds, reached to about 120° C. at t=about 400 seconds, and became in a quasi-steady state of about 130° C. at t=about 1,000 seconds; and the temperature of the battery cover 23 b increased to about 53° C. at t=about 1,000 seconds.

(Simulation Model 2)

With respect to one model of an example of the electronic apparatus of the present invention, simulation was conducted. This model represents the structure of an existing smartphone similarly to Simulation model 1 in the above, but differs significantly in that this model is intended to be equipped with one chemical heat pump. According to the analytical method as in Simulation model 1, this simulation was conducted for the case of CPU heat generation amount of 7 W.

As shown in FIG. 9, this simulation model assumes an electronic apparatus model 31 which is similar to the electronic apparatus model 30 of FIG. 8, with the exception that one chemical heat pump 10 is added so that a reaction chamber 1 and a condensation/evaporation chamber 3 are attached to the CPU 21 a and the chassis (upper heat conductive member) 23 a respectively, and the chassis 23 a is distant from the battery 24 and the camera unit 25. The imaginary routes for allowing heat to move in and out in this electronic apparatus model 31 are shown by double arrows in FIG. 9. It is noted in the electronic apparatus model 31 that the reaction chamber 1 is switchable between a state where it is thermally isolated from other members and a state where it is thermally combined with the CPU 21 a.

With respect to each of the members in the electronic apparatus model 31 other than the chemical heat pump 10, the dimensions and the heat generation amount (the CPU heat generation amount was 7 W only), the values of physical properties such as density, specific heat, thermal conductivity, etc., the mc value, the initial and boundary conditions were similarly set to those in Simulation model 1 described above.

With respect to the chemical heat pump 10, it is set and assumed as follows.

The reaction chamber 1 is composed of a container (outer dimensions of 40 mm×40 mm×2.5 mm, wall thickness of 0.25 mm) made of SUS 304 and filled with 5.23 g of calcium sulfate. The condensation/evaporation chamber 3 is composed of a container (outer dimensions of 15 mm×15 mm×1.5 mm, wall thickness of 0.25 mm) made od SUS 316 and filled with 0.346 g of distilled water. With respect to the reaction chamber 1 and the condensation/evaporation chamber 3, values of physical properties such as density, specific heat, thermal conductivity, etc. were appropriately set corresponding to each of the materials, and mc value (a product of specific heat and mass) was calculated for them and used. The specific heat and the density were assumed to be constant regardless of the temperature.

The thermal contact resistances between the reaction chamber 1 and the CPU 21 a, and between the condensation/evaporation chamber 3 and the chassis 23 a are disregarded.

With respect to the communication part 5 communicating between the reaction chamber 1 and the condensation/evaporation chamber 3, heat transfer between them is disregarded.

For an endothermic reaction of calcium sulfate hemihydrate and an exothermic reaction of calcium sulfate, the known chemical reaction rate equations are applied (Chemical Engineering Proceedings (Kagaku Kogaku Ronbun-shu), Vol. 35, No. 4, pp. 390-395, 2009).

The calcium sulfate hemihydrate/calcium sulfate is assumed to be in the form of spherical particles having an average particle diameter of 0.85 mm, and expansion and contraction of the particles are disregarded.

With respect to water vapor, translational diffusion resistance and the like are disregarded, the temperature in the reaction chamber and the temperature in the condensation/evaporation chamber correspond to the temperatures of the respective chambers, a pressure in the condensation/evaporation chamber corresponds to a pressure of saturated water vapor at that temperature, and a pressure in the reaction chamber corresponds to the pressure in the condensation/evaporation chamber communicated therewith.

In the Case of CPU Heat Generation Amount of 7 W Example 1

Assuming the heat generation amount of the CPU 21 a in the electronic apparatus model 31 at 7 W, simulation of heat balance was conducted by applying the analytical method comprising the various conditions/assumptions described above. In this simulation, the chemical heat pump 10 was intended to be operated at heat release process and then at heat storage process. Change in the temperatures of the CPU and the reaction chamber with the passage of time in this simulation is shown in a graph and a table of FIG. 10B. Specifically, it is explained as follows.

First, based on the initial conditions (t=0), simulation was conducted by assuming the heat generation amount of the CPU 21 a at 7 W and letting the exothermic reaction proceed in the reaction chamber 1 at adiabatic state (thermally disconnect from the CPU 21 a) of the chemical heat pump 10 until the temperature of the CPU 21 a reached to 120° C. (shown with the number (1) in FIG. 10A), and then staring heat exchange (heat transfer) by thermally combining the reaction chamber 1 with the CPU 21 a until the temperature of the CPU 21 a reached to 120° C. again. As the results of this simulation, the followings were shown. The temperature of the CPU 21 a reached to 120° C. at t=about 230 seconds, and during this, calcium sulfate in the reaction chamber 1 reacted with vapor to generate heat at the level of 1.7 W on average while water in the condensation/evaporation chamber 3 evaporated to absorb heat at the level of 2.1 W as the latent heat, and the temperature of the reaction chamber 1 increased to 70° C. at t=about 230 seconds (shown with the number (2) in FIGS. 10A and 10B). Then, by thermally combining the CPU 21 a (120° C.) with the reaction chamber 1 (70° C.) at t=about 230 seconds, the temperature of the CPU 21 a was reduced to 85° C. at t=about 245 seconds (shown with the number (3) in FIGS. 10A and 10B). Since then, calcium sulfate in the reaction chamber 1 continued to react with vapor to generate heat at the level of 1.7 W on average while water in the condensation/evaporation chamber 3 continued to evaporate to absorb heat at the level of 2.1 W as the latent heat, and the temperature of the reaction chamber 1 became 101° C. at t=about 360 seconds (shown with the number (4) in FIGS. 10A and 10B), and the reaction equilibrium pressure reached the saturated vapor pressure at the temperature 16° C. of the condensation/evaporation chamber, and thereby the endothermic reaction in the reaction chamber 1 was completed (reaction rate of about 97%). Then, the temperatures of the CPU 21 a and the reaction chamber 1 (its inside and container) reached to about 120° C. at t=590 seconds (shown with the number (5) in FIGS. 10A and 10B). During this, water in the condensation/evaporation chamber 3 continued to evaporate to absorb heat at the level of 2.1 W as the latent heat, and the temperatures of the condensation/evaporation chamber 3 (its inside and container), the chassis 23 a, and the display 26 were decreased to about 17° C. at t=about 590 seconds. Thus, the chemical heat pump operated at the heat release process during t=0 to 360 seconds (reaction rate of about 97%), and was able to make the temperature of the CPU 21 a at 120° C. or less during t=0 to 590 seconds.

Subsequently (subsequently to the time point of t=590 seconds), simulation was conducted by assuming the heat generation amount of the CPU 21 a at 7 W and keeping thermal combination of the reaction chamber 1 with the CPU 21 a until calcium sulfate hemihydrate in the reaction chamber 1 at 120° C. generated water vapor by absorbing heat to reach the reaction rate of 90%. As the results of this simulation, the followings were shown. In the reaction chamber 1, calcium sulfate hemihydrate absorbed heat at the level of 1.3 W on average to emit water vapor continuously (heat storage), and during t=590 to 1,040 seconds (450 seconds after the start of absorbing heat) (shown with the number (6) in FIG. 10A) the temperatures of the CPU 21 a and the reaction chamber 1 (its container and inside) were maintained at about 120° C. The water vapor generated during this time moved to the condensation/evaporation chamber 3 and emitted heat at the level of 1.6 W as the latent heat on changing into liquid water, and the temperatures of the condensation/evaporation chamber 3 (its container and inside), the chassis 23 a, and the display 26 increased to about 28° C. at t=1,040 seconds. In addition, the temperature of the battery cover 23 b was increased to about 55° C. at t=1,040 seconds. Thus, the chemical heat pump 10 operated at the heat storage process during t=590 to 1,040 seconds (reaction rate of about 90%) and was able retain the temperature of the CPU 21 a at about 120° C.

Therefore, according to this simulation, it was found that by equipment of the chemical heat pump 10, even in the case where the CPU heat generation amount is extremely large as 7 W, the CPU was kept not to exceed 120° C. for the time duration of approximately 1,040 seconds from the start of heat generation by the CPU.

(Simulation Model 3)

With respect to another model of an example of the electronic apparatus of the present invention, simulation was conducted. This model represents the structure of an existing smartphone similarly to Simulation model 1 in the above, but differs significantly in that this model is intended to be equipped with two chemical heat pumps. According to the analytical method as in Simulation model 1, this simulation was conducted for the case of CPU heat generation amount of 7 W.

As shown in FIG. 11, this simulation model assumes an electronic apparatus model 32 which is similar to the electronic apparatus model 30 of FIG. 8, with the exception that two chemical heat pumps 10 and 10′ are added so that a reaction chamber 1 and a reaction chamber 1′ are attached to the CPU 21 a and the battery cover (lower heat conductive member) 23 b respectively, and condensation/evaporation chambers 3 and 3′ are attached to each other. The imaginary routes for allowing heat to move in and out in this electronic apparatus model 32 are shown by double arrows in FIG. 11.

With respect to each of the members in the electronic apparatus model 32 other than the chemical heat pumps 10 and 10′, the dimensions and the heat generation amount (the CPU heat generation amount was 7 W only), the values of physical properties such as density, specific heat, thermal conductivity, etc., the mc value, the initial and boundary conditions were similarly set to those in Simulation model 1 described above.

With respect to the chemical heat pumps 10 and 10′, these are set and assumed as follows, and similar settings and assumptions to those described above with respect to the chemical heat pump 10 in Simulation model 2 shall apply unless otherwise noted. (However, the chemical material charged into the reaction chamber 1 is in the form of calcium sulfate hemihydrate (5.235 g in calcium sulfate equivalent), and the chemical material charged into the reaction chamber 1′ is in the form of calcium sulfate (5.235 g).)

The thermal contact resistances between the reaction chamber 1 and the CPU 21 a, between the reaction chamber 1 and the battery cover 23 b, and between the condensation/evaporation chamber 3 and the condensation/evaporation chamber 3′ are disregarded.

With respect to the communication part 5 communicating between the reaction chamber 1 and the condensation/evaporation chamber 3 and also the communication part 5′ communicating between the reaction chamber 1′ and the condensation/evaporation chamber 3′, heat transfer between them is disregarded.

The condensation/evaporation chamber 3 and the condensation/evaporation chamber 3′ are thermally isolated from other members.

In the Case of CPU Heat Generation Amount of 7 W Example 2

Assuming the heat generation amount of the CPU 21 a in the electronic apparatus model 32 at 7 W, simulation of heat balance was conducted by applying the analytical method comprising the various conditions/assumptions described above. In this simulation, the chemical heat pumps 10 and 10′ was intended not to be operated at the first, and then the chemical heat pump 10 was intended to be operated at heat release process and at the same time the chemical heat pump 10′ was intended to be operated at heat release process. Specifically, it is explained as follows.

First, based on the initial conditions (t=0), simulation was conducted by assuming the heat generation amount of the CPU 21 a at 7 W and not operating the chemical heat pumps 10 and 10′ until the temperature of the CPU 21 a reached to 120° C. As the results, the temperatures of the CPU 21 a and the reaction chamber 1 (its container and inside) reached to 120° C. at t=800 seconds.

Then (subsequently to the time point of t=800 seconds), simulation was conducted by assuming the heat generation amount of the CPU 21 a at 7 W until calcium sulfate hemihydrate in the reaction chamber 1 at 120° C. generated water vapor by absorbing heat to reach the reaction rate of 100%. As the results of this simulation, the followings were shown. In the reaction chamber 1, calcium sulfate hemihydrate absorbed heat at the level of 1.3 W on average to emit water vapor continuously (heat storage), and during t=800 to 1,300 seconds (500 seconds after the start of absorbing heat) the temperatures of the CPU 21 a and the reaction chamber 1 (its container and inside) were maintained at about 120° C. The water vapor generated during this time moved to the condensation/evaporation chamber 3 and emitted heat at the level of 1.6 W as the latent heat on changing into liquid water, but the condensation/evaporation chamber 3 was cooled by the condensation/evaporation chamber 3′ thermally combined therewith and maintained at about 25° C. Thus, the chemical heat pump 10 operated at the heat storage process during t=800 to 1300 seconds (reaction rate of 100%) and was able retain the temperature of the CPU 21 a at about 120° C.

At the same time (subsequently to the time point of t=800 seconds), simulation was conducted until water in the condensation/evaporation chamber 3 evaporated and the time passed to reach t=1,300 seconds. As the results of this simulation, the followings were shown. The water in the condensation/evaporation chamber 3′ absorbed heat at the level of 2.1 W as the latent heat on changing into water vapor, and the water vapor generated thereby moved to the reaction chamber 1′ and reacted with calcium sulfate to generate heat (heat release) at the level of 1.7 W. At t=1,190 seconds (390 seconds after the start of generating heat) the reaction rate reached to 100% and the heat release in the reaction chamber 1′ was completed. During t=800 to 1,190 seconds, the temperature of the condensation/evaporation chamber 3′ (its container and inside) was maintained at about 25° C. The temperature of the battery cover 23 b was increased to about 52° C. at t=1,300 at most, due to effect by a sensible heat of calcium sulfate/calcium sulfate hemihydrate. This was lower the temperature of the battery cover 23 b in the comparative example in Simulation model 1 described above by 1° C. Thus, the chemical heat pump 10′ operated at the heat release process during t=800 to 1,190 seconds (reaction rate of about 100%).

Therefore, according to this simulation, it was found that by equipment of the chemical heat pumps 10 and 10′, even in the case where the CPU heat generation amount is extremely large as 7 W, the CPU was kept not to exceed 120° C. for the time duration of approximately 1,300 seconds from the start of heat generation by the CPU.

The present invention can be suitably applied to mobile electronic devices such as smartphones, cellular phones, tablet devices, laptop computers, portable game machines, portable music players, and digital cameras, but is limited thereto.

This application claims priority to and the benefit of Japanese Patent Application No. 2012-173042, filed Aug. 3, 2012, the entire contents of which is incorporated herein by reference.

-   1, 1 a, 1 b, 1′ Reaction chamber -   2 a Solid phase (including a chemical heat storage material) -   2 b Gas phase (including a condensable component) -   3, 3 a, 3 b, 3′ Condensation/evaporation chamber -   4 a Gas phase (including a condensable component) -   4 b Liquid phase (including a condensable component) -   5, 5 a, 5 b, 5 c, 5′ Communication part -   10, 10′ Chemical heat pump (device) -   11 Heat generating element -   13 Heat conductive member -   20, 21, 22, 23, 24 Electronic apparatus -   21 a CPU -   21 b Power management IC -   22 Electronic circuit board -   23 a Chassis -   23 b Battery cover -   24 Battery -   25 Camera unit -   26 Display -   28 Human body -   29 Ambient atmosphere (air) -   30, 31, 32 Electronic apparatus model 

1. An electronic apparatus comprising: a heat generating element; and a device comprising: a reaction chamber containing a chemical heat storage material showing an endothermic reaction in response to heat emitted by the heat generating element; a condensation/evaporation chamber for condensing or evaporating a condensable component produced from the endothermic reaction of the chemical heat storage material; and a communication part communicating the reaction chamber with the condensation/evaporation chamber such that the condensable component is movable between the reaction chamber and the condensation/evaporation chamber through the communication part.
 2. The electronic apparatus according to claim 1, wherein the communication part is provided with a filter allowing gas to pass through but not substantially allowing solid and liquid to pass through.
 3. The electronic apparatus according to claim 1, wherein the chemical heat storage material is molded or packed in the reaction chamber, and a minimum cross-sectional dimension of the molded or packed chemical heat storage material is larger than a minimum cross-sectional dimension of the communication part.
 4. The electronic apparatus according to claim 1, wherein the condensation/evaporation chamber contains a material capable of trapping liquid, or at least a portion of an inner surface of the condensation/evaporation chamber is made of the material capable of trapping liquid.
 5. The electronic apparatus according to claim 1, wherein the reaction chamber comprises a portion made of a heat conductive material, and the portion made of the heat conductive material is placed in contact with the heat generating element directly or indirectly.
 6. The electronic apparatus according to claim 1, wherein the electronic apparatus further comprises a heat conductive member, and the condensation/evaporation chamber comprises a portion made of a heat conductive material, and the portion made of the heat conductive material is placed in contact with the heat conductive member directly or indirectly.
 7. The electronic apparatus according to claim 6, the heat conductive member is selected from the group consisting of a housing of the electronic apparatus, an exterior of a battery, a substrate and a display.
 8. The electronic apparatus according to claim 1, the heat generating element is selected from the group consisting of an integrated circuit, a light emitting element, a field effect transistor, a motor, a coil, a converter, an inverter and a capacitor.
 9. An electronic apparatus comprising: a first member and a second member; and a device comprising: a reaction chamber containing a chemical heat storage material showing an endothermic reaction and an exothermic reaction reversibly; a condensation/evaporation chamber for condensing or evaporating a condensable component produced from the endothermic reaction of the chemical heat storage material; and a communication part communicating the reaction chamber with the condensation/evaporation chamber; wherein the first member is thermally combined with the reaction chamber, and the condensation/evaporation chamber is thermally combined with the second member.
 10. The electronic apparatus according to claim 9, wherein the communication part is provided with a filter allowing gas to pass through but not substantially allowing solid and liquid to pass through.
 11. The electronic apparatus according to claim 9, wherein the chemical heat storage material is molded or packed in the reaction chamber, and a minimum cross-sectional dimension of the molded or packed chemical heat storage material is larger than a minimum cross-sectional dimension of the communication part.
 12. The electronic apparatus according to claim 9, wherein the condensation/evaporation chamber contains a material capable of trapping liquid, or at least a portion of an inner surface of the condensation/evaporation chamber is made of the material capable of trapping liquid.
 13. The electronic apparatus according to claim 9, wherein when a temperature of the first member is increased and/or a temperature of the second member is decreased, heat is transferred from the first member to the reaction chamber, the chemical heat storage material produces the condensable component by the endothermic reaction in the reaction chamber, the condensable component moves in a gaseous state from the reaction chamber to the condensation/evaporation chamber through the communication part, the condensable component is condensed in the condensation/evaporation chamber to generate heat, and the generated heat is transferred from the condensation/evaporation chamber to the second member.
 14. The electronic apparatus according to claim 9, wherein when a temperature of the first member is decreased and/or a temperature of the second member is increased, heat is transferred from the reaction chamber to the first member, the exothermic reaction occurs to consume the condensable component in the reaction chamber, the condensable component in a gaseous state moves from the condensation/evaporation chamber to the reaction chamber through the communication part, the condensable component condensed in the condensation/evaporation chamber gains the heat and evaporates, and the heat is transferred from the second member to the condensation/evaporation chamber.
 15. The electronic apparatus according to claim 1, wherein the condensable component is water.
 16. An electronic apparatus having a function of suppressing a temperature rise of a heating generating element, comprising: a heat generating element; and at least one reaction chamber containing a chemical heat storage material, wherein heat generated from the heat generating element is transferred from an outer surface of the heat generating element to the chemical heat storage material in the at least one reaction chamber, and the chemical heat storage material absorbs the heat by a reaction to suppress the temperature rise of the heat generating element.
 17. The electronic apparatus according to claim 16, wherein the electronic apparatus comprises a first reaction chamber containing a first chemical heat storage material, and a second reaction chamber containing a second chemical heat storage material, and a first communication part communicating the first reaction chamber with the second reaction chamber, and wherein the first chemical heat storage material and the second chemical heat storage material absorb or generate heat by reactions involving a same component, the first reaction chamber and the second reaction chamber communicate with each other by a the first communication part to allow said component to move through the first communication part, and the heat generated from the heat generating element is transferred to either the first chemical heat storage material in the first reaction chamber or the second heat storage material in the second reaction chamber.
 18. The electronic apparatus according to claim 17, wherein the first chemical heat storage material is molded or packed in the first reaction chamber, and a minimum cross-sectional dimension of the molded or packed first chemical heat storage material is larger than a minimum cross-sectional dimension of the first communication part.
 19. The electronic apparatus according to claim 17, wherein the second chemical heat storage material is molded or packed in the second reaction chamber, and a minimum cross-sectional dimension of the molded or packed second chemical heat storage material is larger than a minimum cross-sectional dimension of the first communication part.
 20. The electronic apparatus according to claim 17, wherein the electronic apparatus further comprises a condensation/evaporation chamber for condensing or evaporating said component, wherein the condensation/evaporation chamber communicates with the first communication part between the first reaction chamber and the second reaction chamber to allow said component to move to and from the condensation/evaporation chamber.
 21. The electronic apparatus according to claim 20, wherein the electronic apparatus further comprises a second communication part communicating the condensation/evaporation chamber with the first communication part, and wherein either the first communication part or the second communication part is provided with a filter allowing gas to path through but not substantially allowing solid and liquid to path through.
 22. The electronic apparatus according to claim 17, wherein the electronic apparatus further comprises a condensation/evaporation chamber for condensing or evaporating said component, and a third communication part communicating the condensation/evaporation chamber with either the first reaction chamber or the second reaction chamber wherein the condensation/evaporation chamber communicates with either the first reaction chamber or the second reaction chamber by the third communication part to allow said component to move to and from the condensation/evaporation chamber.
 23. The electronic apparatus according to claim 22, the third communication part is provided with a filter allowing gas to pass through but not substantially allowing solid and liquid to pass through.
 24. The electronic apparatus according to claim 20, wherein the condensation/evaporation chamber contains a material capable of trapping liquid, or at least a portion of an inner surface of the condensation/evaporation chamber is made of the material capable of trapping liquid.
 25. The electronic apparatus according to claim 20, wherein said component is water.
 26. The electronic apparatus according to claim 1, the chemical heat storage material shows an endothermic reaction at a temperature of 30 to 200° C.
 27. The electronic apparatus according to claim 1, wherein, in place of the chemical heat storage material, the reaction chamber contains at least one heat storage material selected form the group consisting of zeolite, silica gel, mesoporous silica and activated carbon. 